A fart that travels up the entire length of one's buttcrack before "sputtering", "squealing" or going "pop, pop, pop" once it reaches the lower back. This generally occurs when in a sitting position, especially on leather or vinyl.

The Long Haul Trucker (Fart) scenario#1:"Man, I gotta fart, but there's so many people in the car.. I'll just ease one out..Uh, oh! UH OH! "Squeeeeeeeeeal, POP!" Oops.